Is that your main argument against Stack Overflow? Because for some percentage of people the use cases will be similar (that is, learning some quick ways to do something that they can then explore and learn about).
Sometimes resources like these are used as references and the solution is used as is. Sometimes they are used as a survey, and it's more like asking a librarian "I want to learn more about how to X" and having them give a short exposition and point out some sources to study. It's important not to let you view of it's usefulness as one type of resource bleed into your view of how useful it might be for the other.
When one gets snippets from Stack Overflow, he/she doesn't assume it is tailored specifically for the task, so extra check, modification are applied. With copilot people (eventually, especially beginners probably) will assume that the code produced by "magic" AI does exactly what they asked for.
Funnily this problem seems trivial when you have good test coverage for your code. Especially trivial compared to the insane amount of help you could get in writing boilerplate and simple logic from a magical tool like this, if it delivers on its promises.
Sometimes resources like these are used as references and the solution is used as is. Sometimes they are used as a survey, and it's more like asking a librarian "I want to learn more about how to X" and having them give a short exposition and point out some sources to study. It's important not to let you view of it's usefulness as one type of resource bleed into your view of how useful it might be for the other.
As a learning resource, this is very interesting.